Carbonate system properties and anthropogenic carbon inventory in the Algerian Basin during SOMBA cruise (2014): Acidification estimate

Keraghel, Mehdia Asma; Louanchi, Férial; Zerrouki, Mohamed; Kaci, Malik Aït; Aït-Ameur, Nadira; Labaste, Matthieu; Legoff, Hervé; Taillandier, Vincent; Harid, Romaissa; Mortier, Laurent

doi:10.1016/j.marchem.2020.103783

Cited by 10 publications

(16 citation statements)

References 81 publications

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“…The study of Schroeder et al (2008a) showed the presence of these new O 2 -rich deep waters in the Balearic Sea, the Ligurian Sea and in the Algerian sub-basin in June 2005, and their propagation to the whole Algerian sub-basin and the west of the Alboran Sea in October 2006. New oxygenated waters were also observed in the entire deep layers of the Algerian sub-basin in 2011 (Schneider et al, 2014;Stöven and Tanhua, 2015) and 2014 (Keraghel et al, 2020), but were not yet detected in the Tyrrhenian Sea in 2011 (Schneider et al, 2014;Stöven and Tanhua, 2015). Somot et al (2016) found that winter 2012/2013 is one the five winters over the 33 year period 1980-2013 showing high dense water formation rates (above 0.6 Sv), using the CNRM-RCSM4 model.…”

Section: The Role Of the Nw Deep Convection Area In The Ventilation Omentioning

confidence: 95%

Oxygen budget for the north-western Mediterranean deep convection region

Ulses¹,

Estournel²,

Fourrier³

et al. 2020

Preprint

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Abstract. The north-western Mediterranean deep convection plays a crucial role in the general circulation and biogeochemical cycles of the Mediterranean Sea. The DEWEX (DEnse Water EXperiment) project aimed to better understand this role through an intensive observation platform combined with a modelling framework. We developed a 3 dimensional coupled physical and biogeochemical model to estimate the cycling and budget of dissolved oxygen in the entire north-western Mediterranean deep convection area over the period September 2012 to September 2013. After showing that the simulated dissolved oxygen concentrations are in a good agreement with the in situ data collected from research cruises and Argo floats, we analyze the seasonal cycle of the air-sea oxygen exchanges, as well as physical and biological oxygen fluxes, and we estimate an annual oxygen budget. Our study indicates that the annual air-to-sea fluxes in the deep convection area amounted to 20 mol m−2 yr−1. 88 % of the annual uptake of atmospheric oxygen, i.e. 18 mol m−2, occurred during the intense vertical mixing period. The model shows that an amount of 27 mol m−2 of oxygen, injected at the sea surface and produced through photosynthesis, was transferred under the euphotic layer, mainly during deep convection. An amount of 20 mol m−2 of oxygen was then gradually exported in the aphotic layers to the south and west of the western basin, notably, through the spreading of dense waters recently formed. The decline in the deep convection intensity in this region predicted by the end of the century in recent projections, may have important consequences on the overall uptake of atmospheric oxygen in the Mediterranean Sea and on the oxygen exchanges with the Atlantic Ocean, that appear necessary to better quantify in the context of the expansion of low-oxygen zones.

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Section: The Role Of the Nw Deep Convection Area In The Ventilation Omentioning

confidence: 95%

Oxygen budget for the north-western Mediterranean deep convection region

Ulses¹,

Estournel²,

Fourrier³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…The implementation of the hydrodynamic and biogeochemical simulations used in this study was described by Estournel et al (2016a) and Kessouri et al (2017;. The numerical domain (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The biogeochemical model Eco3M-S is a multi-nutrient and multi-plankton functional type model that simulates the dynamics of the biogeochemical decoupled cycles of several biogenic elements (carbon, nitrogen, phosphorus, silicon) and of non-Redfieldian plankton groups (Ulses et al, 2016). The model was previously used to study the biogeochemical processes on the Gulf of Lion shelf (Auger et al, 2011) and in the NW Mediterranean deep-convection area (Herrmann et al, 2013(Herrmann et al, , 2017Auger et al, 2014;Ulses et al, 2016;Kessouri et al, 2017Kessouri et al, , 2018. In this study, the model was extended to describe the dynamics of dissolved oxygen in the ocean interior and the air-sea exchanges of oxygen.…”

Section: The Biogeochemical Modelmentioning

confidence: 99%

“…At the Mediterranean basin scale, the deep convection occurring in the north-western region is one of the major processes responsible for an enrichment of the euphotic layer with nutrients, compared to Atlantic influx as well as terrestrial and atmospheric inputs (Severin et al, 2014;Ulses et al, 2016;Kessouri et al, 2017). The replenishment of the surface layer with nutrients during deep convection is followed by an intense bloom in spring when vertical mixing weakens (Bernadello et al, 2012;Lavigne et al, 2013;Auger et al, 2014;Ulses et al, 2016;Kessouri et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Oxygen budget of the north-western Mediterranean deep- convection region

et al. 2021

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Abstract. The north-western Mediterranean deep convection plays a crucial role in the general circulation and biogeochemical cycles of the Mediterranean Sea. The DEWEX (DEnse Water EXperiment) project aimed to better understand this role through an intensive observation platform combined with a modelling framework. We developed a three-dimensional coupled physical and biogeochemical model to estimate the cycling and budget of dissolved oxygen in the entire north-western Mediterranean deep-convection area over the period September 2012 to September 2013. After showing that the simulated dissolved oxygen concentrations are in a good agreement with the in situ data collected from research cruises and Argo floats, we analyse the seasonal cycle of the air–sea oxygen exchanges, as well as physical and biogeochemical oxygen fluxes, and we estimate an annual oxygen budget. Our study indicates that the annual air-to-sea fluxes in the deep-convection area amounted to 20 molm-2yr-1. A total of 88 % of the annual uptake of atmospheric oxygen, i.e. 18 mol m−2, occurred during the intense vertical mixing period. The model shows that an amount of 27 mol m−2 of oxygen, injected at the sea surface and produced through photosynthesis, was transferred under the euphotic layer, mainly during deep convection. An amount of 20 mol m−2 of oxygen was then gradually exported in the aphotic layers to the south and west of the western basin, notably, through the spreading of dense waters recently formed. The decline in the deep-convection intensity in this region predicted by the end of the century in recent projections may have important consequences on the overall uptake of atmospheric oxygen in the Mediterranean Sea and on the oxygen exchanges with the Atlantic Ocean, which appear necessary to better quantify in the context of the expansion of low-oxygen zones.

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“…The accuracy of measurement of the CTD unit is about 1 dbar in pressure, 0.001 • C in temperature and 0.003 in salinity. The PEACETIME shipboard dataset is complemented with CTD profiles collected during three earlier cruises with the same instrumental package, Med-SeA (Ziveri and Grelaud, 2015) in May 2013, SOMBA-GE (Mortier et al, 2014;Keraghel et al, 2020) in August 2014 and BioArgoMed (Taillandier et al, 2018) in May 2015.…”

Section: Ctd Profilesmentioning

confidence: 99%

Profiling float observation of thermohaline staircases in the western Mediterranean Sea and impact on nutrient fluxes

Taillandier¹,

Prieur²,

D’Ortenzio³

et al. 2020

Biogeosciences

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Abstract. In the western Mediterranean Sea, Levantine intermediate waters (LIW), which circulate below the surface productive zone, progressively accumulate nutrients along their pathway from the Tyrrhenian Sea to the Algerian Basin. This study addresses the role played by diffusion in the nutrient enrichment of the LIW, a process particularly relevant inside step-layer structures extending down to deep waters – structures known as thermohaline staircases. Profiling float observations confirmed that staircases develop over epicentral regions confined in large-scale circulation features and maintained by saltier LIW inflows on the periphery. Thanks to a high profiling frequency over the 4-year period 2013–2017, float observations reveal the temporal continuity of the layering patterns encountered during the cruise PEACETIME and document the evolution of layer properties by about +0.06 ∘C in temperature and +0.02 in salinity. In the Algerian Basin, the analysis of in situ lateral density ratios untangled double-diffusive convection as a driver of thermohaline changes inside epicentral regions and isopycnal diffusion as a driver of heat and salt exchanges with the surrounding sources. In the Tyrrhenian Sea, the nitrate flux across thermohaline staircases, as opposed to the downward salt flux, contributes up to 25 % of the total nitrate pool supplied to the LIW by vertical transfer. Overall, however, the nutrient enrichment of the LIW is driven mostly by other sources, coastal or atmospheric, as well as by inputs advected from the Algerian Basin.

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Carbonate system properties and anthropogenic carbon inventory in the Algerian Basin during SOMBA cruise (2014): Acidification estimate

Cited by 10 publications

References 81 publications

Oxygen budget for the north-western Mediterranean deep convection region

Oxygen budget for the north-western Mediterranean deep convection region

Oxygen budget of the north-western Mediterranean deep- convection region

Profiling float observation of thermohaline staircases in the western Mediterranean Sea and impact on nutrient fluxes

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